Power consumption of a liquid crystal panel of known technique is always a great concern to product design, system verification and client use. Also, reduction of power consumption is always a very important process in product design. In the use of known technique in a device such as a display, notebook, PAD or mobile phone, after the device is in standby for a certain time, the system realizes brightness reduction of the panel by means of reducing backlight brightness or by other means, so as to achieve the purpose of saving power consumption. When the known technique uses a liquid display panel timing control chip compliant with an eDPI.3 interface standard, it adopts a single chip integrated memory to support a panel-self-refresh (PSR) function. The system can enter a PSR mode when displaying a still picture. At this time, the timing control chip will take over a graphics processor to refresh the picture through a built-in buffer storage, so as to reduce load on the graphics processor, so that the graphics processor and the display interface can enter in a low power consumption state to reduce the overall power consumption of the system. Also, the system can update and store a new still picture into the buffer storage through the graphics processor, or get out of the PSR mode to display the constantly changing images, so as to effectively reduce the power consumption of the system and prolong service time of the battery of a notebook computer.
In the liquid crystal panel design of the known technique, an analogy voltage source AVDD used by the liquid crystal panel generally outputs an alternating current AC signal with certain frequency by a converter from a direct current signal to another direct current signal, i.e., a DC-DC converting circuit, to control and generate the required AVDD voltage, and feeds back magnitude of the output voltage to a duty ratio control circuit by an output voltage sampling circuit. Then, the duty ratio control circuit controls the output voltage of the DC-DC converting circuit according to the feedback of the output voltage sampling circuit, so as to guarantee the voltage output by the AVDD output terminal to be maintained at a constant value.
To sum up, the voltage output by the AVDD output terminal needed for the liquid crystal panel of the known technique is constant. When a signal that the system instructs the panel to reduce backlight or perform PSR output is received, it is disadvantageous for reducing the power consumption of the system because the voltage value of AVDD keeps unchanged.